Fireproof plate and a clamping device for a sliding gate at the outlet of a vessel containing molten metal

ABSTRACT

A refractory plate for a sliding gate valve at the outlet of a vessel containing molten metal has a polygonal external shape and has a longitudinal axis, on both sides of which at least two side surfaces, disposed at an obtuse angel (γ) to one another, extend and serve as clamping surfaces of the plate in a metallic frame (11) or the like. The shorter side surfaces are arranged to extend at an angle (α) of between 20° and 50° to the longitudinal axis while the longer side surfaces are arranged to extend at an angle (β) of between 10° and 30° to the longitudinal axis. The refractory plate can thus be optimally clamped and an increased service life is thus consequently achieved.

BACKGROUND OF THE INVENTION

The invention relates to a refractory plate for a sliding gate valve.

A refractory plate, which is not surrounded by a metallic band, isprovided in a sliding gate valve as disclosed in DE-C2 35 22 134. Atleast two opposing regions of an edge of the plate taper towards asliding surface. These tapering edge regions are intended for engagementwith a matching, bevelled surface of a clamping element. The dimensionsand angles of the plate are so selected in the region of the bevelledsurfaces from the sliding surface to a rear engagement surface that theclamping elements exert a force component directed not only towards thecenter of the plate but also towards the rear engagement surface. Theplate can have a rectangular shape with rounded corners or a hexagonalshape which is constituted by two equal sided trapeziums with a commonbase.

This known way of clamping refractory plates in a sliding gate valve isassociated with various disadvantages. On the one hand, a number ofclamping elements provided for clamping the plate are tightenedindividually against corresponding edge regions of the plate by means ofscrews or the like. This results in a disproportionate amount of work inthe installation process. Furthermore, satisfactory functioning of thescrews and the threaded holes in the long term is not guaranteed in theextremely rough and hot operating environment. Furthermore, therefractory plates with the bevels provided in their edge regions arerelatively expensive to manufacture, and the sharp plate edges caused bythese bevels can easily break away, particularly on impact.

SUMMARY OF THE INVENTION

Against this background, it is the object of the present invention toprovide a refractory plate of the type referred to above, but which canbe easily manufactured and has such an external shape that optimumcompressive stress conditions are present in the plate in the clampedand heated operational state and that an increased service life isconsequently achieved. A sliding gate valve accommodating such platesshould be equipped with a clamping device with which these plates may besimply and rapidly clamped.

The object is solved in accordance with the invention by the provisionsof a refractory plate having a polygonal external shape and alongitudinal axis, on both sides of which extend at least two sidesurfaces of different length, which are arranged at an obtuse angle (γ)to one another and act as clamping surfaces of the plate in a metallicframe or the like. The shorter side surfaces are arranged to extend atan angle α of between 20° and 50° to the longitudinal axis, while thelonger side surfaces are arranged to extend at an angle β of between 10°and 30° to the longitudinal axis.

A clamping device is preferably provided for the clamping of the platein the sliding gate valve and has clamping elements which, for thepurpose of achieving engagement with the side surfaces of the refractoryplate over their entire area, are pivotally mounted in a frame. At leasttwo of the clamping elements are guided to be movable by a singleclamping means towards the other two clamping elements.

Optimal clamping and thus an improved service life of the plate areachieved with this construction of the refractory plate in accordancewith the invention and the clamping device holding the plate. Theclamping of the plate is optimized by the force application producedover almost the entire length of the plate and by the pattern of linesof force acting on the plate at selected angles. Cracks produced in theplate in the operational state thus do not break up, and the sucking ofair in through these cracks can be substantially prevented. As a resultof the fact that the plate has no sheet metal shell, it may befabricated economically.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the invention and further advantages thereofwill be explained in more detail below with reference to the drawings,in which:

FIG. 1 is a plan view of a refractory plate in accordance with theinvention mounted in a metallic frame;

FIG. 2 is a side view of the plate of FIG. 1 mounted in the frame;

FIG. 3 is a plan view of a sliding gate valve housing with a clampingdevice for clamping the plate of FIG. 1;

FIG. 4 is a plan view of a modified plate mounting; and

FIG. 5 is a sectional view of the plate mounting of FIG. 4.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a refractory plate 20 with a flow opening 22 clamped in ametallic frame 11. This plate 20 may be inserted as a base plate or asliding plate into a sliding gate valve, which is not shown in detail,at the outlet of a vessel containing molten metal. Such a sliding gatevalve is illustrated and described in detail, for instance in thepublication EP-B1 0277146. It is used, in particular, for ladlescontaining molten metal which are conventionally provided in continuouscasting installations. The refractory plate 20 comprises heat-resistantceramic material and it can be manufactured in one piece or from a basematerial with at least one high grade refractory insert, this refractoryinsert advantageously defining the flow opening 22 through which themolten steel flows in the operational state of the plate.

In the present exemplary embodiment the plate 20 has a hexagonalexternal shape with an elongate symmetrical construction. Extending onboth sides of longitudinal axis 23 of the plate are two respective sidesurfaces 24, 25 of different length, which are disposed at an obtuseangle γ to one another and serve as clamping surfaces for the plate 20in the metallic frame 11. In accordance with the invention, the shorterside surfaces 24 are each arranged to extend at an angle α of between20° and 50° to the longitudinal axis 23, while the longer side surfaces25 are each arranged to extend at an angle β of between 10° and 30° tothe longitudinal axis 23. In the actual advantageous exemplaryembodiment the angle α is approximately 30° and the angle β isapproximately 14°. The shorter and longer side surfaces 24, 25 serve asclamping surfaces for the plate 20 in the metallic frame 11 and definetherebetween a transverse edge 26. Between the shorter and longer sidesurfaces 24 and 25, respectively, the ends of the plate is formed withrespective end surfaces 27, 28 extending perpendicular to thelongitudinal axis 23. These end surfaces 27, 28 have a length ofapproximately half the width of the plate. After clamping the plate 20in the frame 11, end surfaces 27, 28 are not contacted and thus notclamped to the metallic frame 11.

The flow opening 22 is disposed perpendicularly on the longitudinal axis23 and has a diameter which is about one-third to one-quarter of thebreadth of the plate. Flow opening 22 is offset from the center of theplate 20 towards the shorter side surfaces 24 with respect to thelongitudinal dimension of the plate. The center of opening 22 liesapproximately on the angular bisector which is defined by the obtuseangle γ between the shorter and longer side surfaces 24, 25. A spacingof about one-third of the length of the plate is provided between theopening 22 and the end surface 27 which connects the two shorter sidesurfaces 24.

The metallic frame 11 comprises two frame portions 11' of the samedimensions, two clamping shoes 12 pivotally mounted on the latter andtwo threaded bolts 14 connecting the two frame portions. The threadedbolts are pivotally mounted laterally on a respective frame portion 11'and extend through a bore provided in the other frame portion 11'. Thebolted together frame portions and the clamping shoes 12 define anopening which corresponds to the external shape of the plate and inwhich the plate 20 can be clamped. The frame 11 with the plate 20clamped therein can be inserted into a housing of the sliding gatevalve, only two centering pegs 16, 17 of which are illustrated. The oneframe portion 11' has a corresponding bore to receive the peg 16 whilethe other frame portion conveniently has a longitudinal groove 18 inwhich the peg 17 is centered so that the frame can expand, at least inthe longitudinal direction, in the housing as a result of the heatproduced in the operational state. After the plate 20 has become worn,it can be removed together with the frame, and the frame can be reusedwith a new plate clamped therein.

This described construction of the frame 11 makes possible clamping ofthe plate therein with shorter and longer side surfaces 24, 25respectively engaging the clamping shoes or the frame portions overnearly their entire length, particularly even if the external dimensionsof the plate vary by a few millimeters due to manufacturing reasons.This can be ensured by appropriate adjustment of the threaded bolts 14.This results in a further advantage of the present invention in thatside surface of the plate need not be manufactured to narrow tolerances.

As shown in FIG. 2, the plate 2 has two plane parallel surfaces 21, 29,at least one of which is ground. The upper or lower surface 21, 29 actsas a sliding surface which is in sliding contact, in the operationalstate of the plate, with a similar second plate. When the one platemoves in the direction of its longitudinal axis 23, the flow openingsare moved more or less into registry, in an open position, and out ofregistry, in a closed position. Connected to the surface 29 opposite tothe sliding surface there is in general a refractory sleeve 32 which isshown in chain-dotted lines. For a satisfactory seal between the plateand this sleeve the plate can have a recess, in a manner known per se,in the region of the flow opening to accommodate the sleeve or ashoulder projecting into the sleeve.

The external shape of the plate could in principle also be defined byless or more than six corners and, for example, could be octagonal,whereby in this case the additional surfaces would advantageously beformed between the shorter and the longer side surfaces 24, 25 andarranged approximately parallel to the longitudinal axis 23. Theposition of the flow opening 22 with respect to the longitudinal axis 23could also be disposed, for instance, on the connecting line between theedges 26 or in a different position.

FIG. 3 shows a clamping device 40 integrated into a slider housing 19for releasably securing the refractory plate 20. This clamping device 40has four clamping elements 42, 44 which are arranged in housing 19 andwhich afford respective clamping surfaces which are pressed, in theclamped state, against corresponding side surfaces 24, 25 of the plate20. In accordance with the invention, these clamping elements 42, 44 arepivotally mounted in the housing 19 for the purpose of achievingengagement over their whole area with the side surfaces 24, 25 of theplate 20, and two of the clamping elements 44 are guided to be movableby a single clamping means towards the other two clamping elements 42.Each triangularly shaped clamping element 42, 44 has a clamping surfaceon its base side, and one or both of its rear sides is slightly dishedor convex to engage abutment surfaces 19' on the housing 19. For pivotalmounting elements 42, 44 are provided with longitudinal grooves 48,which are aligned parallel with the longitudinal axis 23 and in whichpegs 45, 46 projecting from housing 19 are centered in an approximatelyclearance-free manner. When clamping a plate 20, clamping elements 42,44 thus adopt automatically the effective angle α or β of a side surface24, 25 and consequently ensure engagement over their whole area, whichresults in uniform pressure distribution of the clamping force on theplate, which maximizes the service life of the plate.

The two movable clamping elements 44 on the longer side surfaces 25 areconnected via respective levers 51 to sliding blocks 52 which are inengagement with a threaded rod 53 which is transverse to the directionof movement of the clamping elements 44 and is rotatably mounted on thehousing 19. When threaded rod 53 is rotated, the two sliding blocks 52move either inwardly or outwardly as a result of opposite-handed threadsprovided therein. In the event of outward movement, the clampingelements 44 are pressed by the levers 51 against the plate 20 and theplate is thus clamped, whilst in the case of inward movement the plateis released. The rotation of the threaded rod 53 can be effected bymeans of a manually actuated key or by means of an automatically actingdevice which is not shown in detail. The clamping surfaces of theclamping elements 42, 44 are so dimensioned that they overlap the sidesurfaces of the refractory plate and are in contact with them overalmost their entire length, but advantageously have a somewhat smallerlength than the corresponding side surfaces 24, 25 of the plate and, inthe clamped state, engage between the ends of the side surfaces 24, 25without contacting lateral plate edges 26, 28' in order to prevent theformation of cracks at such edges.

FIG. 4 and FIG. 5 illustrate a modification of the clamping element 42and of the plate 20 cooperating therewith. The plate 20 has a chamfer20' which extends over the shorter side surface 24 and is intended forengagement by a retaining element 43 secured to the clamping element 42.The plate 20 is thus prevented from falling out when it is in thereleased state and the slider housing 19 and the plate 20 with it,viewed in the longitudinal direction, are located in a verticalinstallation position.

Other modifications of clamping devices may of course also be used.However, the comments set forth are sufficient to explain the invention.The plate could be surrounded on its narrow side, for instance with aband, so that it does not fall apart after use during disassembly inwhich the clamping elements are released. For the purpose of insulation,the plate could also be provided at this narrow side and/or at the rearside 29 with a flexible coating, e.g. a Pyrostop paper.

What is claimed is:
 1. A refractory plate for use in a sliding gatevalve for controlling the discharge of molten material from a vessel,said plate comprising:a polygonal external shape and a longitudinalaxis; at least two side surfaces of different length on each side ofsaid longitudinal axis; said side surfaces on each side of saidlongitudinal axis extending at an obtuse angle γ to each other; ashorter said side surface on each side of said longitudinal axisextending at an angle α of between 20° and 50° to said longitudinalaxis; a longer said side surface on each side of said longitudinal axisextending at an angle β of between 10° and 30° to said longitudinalaxis; a first end surface extending perpendicular to said longitudinalaxis and connected to said shorter side surfaces; a second end surfaceextending perpendicular to said longitudinal axis and connected to saidlonger side surfaces; said shorter side surfaces and said longer sidesurfaces comprising clamping surfaces operable to be clamped by a frameto mount said plate in the sliding gate valve; and said first endsurface and said second end surface comprising unclamped surfacesoperable to not be clamped by the frame.
 2. A plate as claimed in claim1, wherein said angle α is approximately 30° and said angle β isapproximately 15°.
 3. A plate as claimed in claim 1, wherein said shapeis symmetrical with respect to said longitudinal axis.
 4. A plate asclaimed in claim 1, wherein said shape is hexagonal.
 5. A plate asclaimed in claim 1, wherein at least one said side surface has a bevel.6. A plate as claimed in claim 1, further comprising a flow openingarranged on said longitudinal axis at a location closer to said firstend surface than to said second end surface.
 7. A plate as claimed inclaim 1, wherein said first end surface and said second end surface havesubstantially equal lengths.
 8. A plate as claimed in claim 1, whereinsaid first end surface and said second end surface have lengths equal toapproximately one-half of a width of said plate.
 9. An assembly for usein a sliding gate valve for controlling the discharge of molten materialfrom a vessel, said plate comprising:a refractory plate having apolygonal external shape and a longitudinal axis, at least two sidesurfaces of different length on each side of said longitudinal axis,said side surfaces on each side of said longitudinal axis extending atan obtuse angle γ to each other, a shorter said side surface on eachside of said longitudinal axis extending at an angle α of between 20°and 50° to said longitudinal axis, a longer said side surface on eachside of said longitudinal axis extending at an angle β of between 10°and 30° to said longitudinal axis, a first end surface extendingperpendicular to said longitudinal axis and connected to said shorterside surfaces, a second end surface extending perpendicular to saidlongitudinal axis and connected to said longer side surfaces; and aclamping device for releasably mounting said plate in the sliding gatevalve, said clamping device comprising a frame, at least four clampingelements pivotally mounted in said frame and defining clamping surfacesthat, in a clamped state, contact respective of said side surfaces ofsaid plate over substantially entire areas of said clamping elements,and a single clamping member for moving at least two of said clampingelements toward the other of said clamping elements.
 10. An assembly asclaimed in claim 9, wherein said clamping elements have lengths that aresomewhat smaller than lengths of respective said side surfaces, and eachsaid clamping element engages, in said clamped state, the saidrespective side surface between opposite ends thereof.
 11. An assemblyas claimed in claim 9, wherein said clamping member is actuableautomatically.
 12. A clamping device for releasably mounting arefractory plate in a sliding gate valve to be employed for controllingthe discharge of molten material from a vessel, said clamping devicecomprising:a frame; at least four clamping elements pivotally mounted insaid frame and defining clamping surfaces operable to, in a clampedstate of said clamping device, contact respective side surfaces of therefractory plate over substantially entire areas of said clampingelements; and a single clamping member for moving at least two of saidclamping elements toward the other of said clamping elements.
 13. Aclamping device as claimed in claim 12, wherein said clamping elementshave lengths to be somewhat smaller than lengths of respective sidesurfaces of the refractory plate, such that each said clamping elementis operable to engage, in said clamped state, the respective sidesurface of the refractory plate between opposite ends thereof.
 14. Anassembly as claimed in claim 12, wherein said clamping member isactuable automatically.